My head is swirling with scenarios and plots, but they vanish when I try to write. How do I fix this?

Hi everyone, I’m 21 years old. ​I’ve consumed a huge amount of media throughout my life—books, novels, TV series, movies, and manga. The problem is, whenever I watch or read something mediocre or subpar, I get really frustrated. I always catch myself thinking, "If I wrote a story, it would be much better than this." ​This mindset has my brain constantly churning out plots and scenarios. But here is the issue: the moment I actually sit down to write, the plot seems to evaporate. I get hit with a wave of frustration that stops me from continuing. ​For context, I haven’t actually written much before. I just feel like my words fail to capture the ideas in my head, and I’m unable to offload all these thoughts into actual, useful writing. ​Has anyone else dealt with this? What is the solution?